This invention relates to a coordinate position detecting device that detects a touch position coordinate in a scanning plane for each frame of the scanning plane and a display input device including the same.
Some of the coordinate position detecting devices such as a touch screen set a frame rate representing the number of detections per unit time of a touch position coordinate in a scanning plane, and detect the touch position coordinate for each frame at a speed of the frame rate.
A known example of each a coordinate position detecting device is an optical touch screen that is configured to increase the scanning speed when a user moves the touch position quickly (for example, see Japanese published unexamined application No. 2006-11568). This optical touch screen skips some of the intervals of the detection pitches of a light emitting device and a light receiving element to increase the scanning speed.
An optical touch screen is also known in which if the user moves the touch position at a low speed, a detection beam emitted from one light emitting device is sequentially detected by up to five light receiving elements, and at a higher moving speed, a detection beam emitted from one light emitting device is detected by less light receiving elements (for example, Japanese published unexamined application No. 2007-65767).
However, No. 2006-11568 describes a conventional coordinate position detecting device that is intended to reduce the time necessary to scan one frame, but does not consider the scanning time interval between frames. In addition, if the touch position moves at a high speed, some of the intervals of the detection pitches are skipped to increase the scanning speed, thus reducing the scanning accuracy.
No. 2007-65767 also describes a conventional coordinate position detecting device that is intended to reduce the time necessary to scan one frame, but does not consider the scanning time interval between frames. In addition, when the touch position moves at a higher speed, a detection beam emitted from one light emitting device is detected by less light receiving elements, thus reducing the scanning accuracy.
It is therefore an object of the present invention to provide a coordinate position detecting device that reduces the processing load of the position detection for power saving and improved scanning accuracy, and a display input device including the same.